Evaluation of Metal Leaching from End-of-Life Laptop Computers Using the TCLP and Other Standard Leaching Tests

The proper management of discarded electronic devices (often called electronic waste) is an emerging issue for solid waste professionals throughout the world because of the large growth of the waste stream, and the content of toxic metals in them, most notably heavy metals such as lead. Laptop computers are becoming one of the components of discarded electronic devices and will continue to increase in the waste stream in the future. The objective of this study was to examine leaching potential of metals from discarded laptop computers using the scale-up toxicity characteristic leaching procedure (TCLP), other standard leaching tests such as California waste extraction test (Cal WET), and the synthetic precipitation leaching procedure (SPLP) and actual landfill leachates as leaching solution. The results showed that the scale-up TCLP resulted in relatively high lead found in the leachate with an average of 23.3 mg/L. The average level was less than those by the standard TCLP and WET (37.0 mg/L and 86.0 mg/L, respectively), but much greater than those by the SPLP and the extractions with the landfill leachates (0.55 mg/L and 1.47 mg/L, respectively). All other target metals (Ag, As, Ba, Cd, Cr, Hg, Se) were found to be either less than or close to their detection limits. The pH of the leaching solution and the ability of the organic acids in the TCLP and WET to complex with lead were identified as major factors that controlled the amount of lead leached from laptop computers